Evaporator



c. E. LIPMAN April 10, 1934;

EVAPOR AT OR Filed Aug- 22, 1930 3 Sheets-Sheet 2 April 1934- c. E. L. LIPMAN 1,954,015

, EVAPORATOR wg y -MWMMQWM Patented Apr. 10, 1934 UNITED STATES EVAPORATOR Carl E. L. Lipman, Chicago, Ill., assignor to Lipman Patents Corporation, Chicago, Ill., a corporation of Delaware Application August 22, 1930, Serial No. 477,044

11 Claims. (01. 62-426) This invention relates to evaporators and has for its purpose the provision of an evaporator that'will efiiciently refrigerate two or more compartments at different temperatures such as a so-called freezing compartment and a storage compartment.

It is an object of this invention to provide an eflicient evaporator which will require relatively little refrigerant and which will prevent the accumulation of sufficient oil therein to interfere with proper functioning of the evaporator and which will provide for the return of any substantial amounts of oil that may appear therein.

It is also an object of this invention to provide an evaporator that is non-dehydrating and selfdefrosting.

. In accordance with this invention the evaporator is composed of a plurality of shells so spaced and arranged as to provide two or more spaced relatively thin intercommunicating refrigerant chambers, one at least of which comprises a plurality of grooves or refrigerant ducts. If desired the chambers may be so arranged that there is no heat interchanged between the shells comprising one chamber and the shells comprising the other chamber except at the point of communication therebetween. Means may also be provided if desired for insuring a continuous circulation in one direction in one or more of the chambers.

The physical size and arrangement of the ducts comprising one or more of the chambers is preferably so designed as to cause the removal of any substantial accumulation of oil therein by what may be termed a combination of a suction and an injection action to return the oil back to the compressor through the suction line and to thereby prevent the permanent accumulation of any substantial amounts of oil as would preclude efiicient operation of the evaporator,

A better and complete understanding of this invention will be had from a consideration of the following detailed description given in connection with the drawings in which:

Fig. 1 is a front elevation of an evaporator constructed in accordance ,with this invention.

Fig. 2 is a longitudinal vertical section taken on line 2-2 of Fig. 1.

Fig. 3 is a section taken on line 3--3 of Fig. 1.

Fig. 4 is a section on line 4-4 of Fig. 3. v

Fig. 5 is a similar section as Fig. 4, showing a slight modification of the invention.

Fig. 6 is a section similar to Fig. 2 but looking in the opposite direction showing a further modifled form of the invention, and

Fig. 7 is a section on line 77 of Fig. 6.

Referring to the drawings and more particularly to Figs. 1, 2, 3 and 4 it will be seen that the evaporator comprises four rectangularly shaped cylindrical shells 1, 2, 3 and 4 nested concentrically one within the other. The shells 2 and 4 are corrugated transversely and securedrespectively to shells 1 and 3 at their ends. The shells of each pair are secured together at their ends and between the corrugations thus leaving a series of ducts 6 which constitute the inner refrigerant chamber and a second series of relatively smaller ducts 7 which constitute an outer refrigerant chamber spaced from the inner refrigerant chamber. The combined total cross-sectional area of all the smaller ducts is preferably, although not necessarily, substantially equal to the area of the suction tube for reasons stated later. The two pairs of shells are retained in spaced relation by end headers 8 one end of the inner shell 1 also being closed by a header 9 thus providing an inner compartment or freezing chamber adapted to receive trays 11. Fins 13 may be attached to the outer corrugated shell 4. If desired the chamber 12 between the two pairs of shells headers 8 may be evacuated or filled with vapor,- liquid, or solid material to prevent condensation therebetween and to prevent transfer of heat from the inner chamber to the outer chamber.

As can be seen from Fig. 4, 'shells 2 and 3 are provided with a passage 16 along the top thereof which establish communication between ducts 6 and 7. This passage extends along the top of the evaporator and is defined by side walls 17. The outer shell 4 is also provided with a raised portion or dome 18 which extends across the top of the evaporator transversely to ducts '7 and establishes communication with each of the ducts '7. Adjacent one side of the dome 18 the outer wall 4 is depressed into contact with shell 3 as at 19 to seal off all of the corrugations to provide for a circulation therethrough in one direction as will be hereinafter more fully explained.

The suction line 21 of the refrigerating system may be attached to the dome at any convenient point, preferably one end, and the liquid supply line 22 may be brought in through the'top of the two shells 3 and 4 to project into passage 16.

The operation of the evaporator just described is as follows: liquid refrigerant such as sulphur dioxide isfed into inner corrugations 6 through inlet pipe 22 projecting into passage 16. The refrigerant will of course flow through the corruga tions and fill the inner chamber. The supply is regulated by a suitable float or valve to terminate the supply when the inner corrugations are substantially full. When the compressor of the system is operating a suction will be created in pipe 21 and accordingly in dome 18; The refrigerant in the inner corrugations 6'will then boil, some passing over into the outer corrugations '7. The refrigerant which gets into duct 7 will pass along the top thereof, down one side, along the bottom, and up the other side into drum 18. The de-' pressed portion 19 prevents the passage of the refrigerant across the top and directly into drum 18.

The liquid passing from within the inner chamber into the outer chamber will of course wet the sides of the outer corrugations. The outer corrugations will absorb heat from the storage compartment and refrigerate the same. The inner corrugations which contain the main body of the liquid will refrigerate the inner compartment to a lower degree and will therefore provide the necessary cooler temperatures within the freezing compartment. During idle periods of the compressor the refrigerant which has wetted the sides .of the outer corrugations will vaporize and seek the cooler or inner corrugations where the vaporized gases will recondense.

There being no body of liquid refrigerant permanently in the outer corrugations the outer corrugations and fins attached thereto will accordingly be self-defrosting. In view of the limited amount of refrigerant which is spread over a rela-- tively large area of the outer corrugations and fins the temperature of the outer ducts and fins need not be below freezing temperature and therefore will not produce an appreciable amount of frost. The evaporator is therefore substantially non-dehydrating.

If any oil should come over with the liquid refrigerant it will of course float on top of the refrigerant during idle moments of the compressor and during working periods will be carried over by the boiling of the refrigerant therewith by emulsifying or atomizing. The oil will thus eventually get into the outer ducts 7. When suction is applied during working periods of the compressor each duct 7 will constitute a restricted tube having a suction applied thereto and accordingly the oil contained in these ducts will be partially sucked and partially injected or inspirated into dome 18 and suction line 21 and returned to the compressor. This action is particularly noticeable when the total combined areas of the ducts 7 are of the order of the cross-sectional area of the suction line. The provision of this relation between the refrigerant ducts and the suction tube has several novel advantages. In some respects this arrangement brings about the effect of a single tube without the disadvantages of a single tube. If a single continuous tube were used and a quantity of oil got over into the lowest loop or portion thereof, it would be impossible to suck all of the oil out of the loop and what oil would come over into the suction tube would be in the form of large slugs which would be detrimental to the compressor. The utilization of a plurality of small tubes, the total area of which is only equal to the suction tube, minimizes the total amount of oil which may betrapped in the evaporator and therefore prevents robbing the compressor of oil since the oil will be more readily withdrawn from the evaporator in relatively small portions which will clear the evaporator of oil and remove it in such small quantities as not to be detrimental to the compressor. This feature obviously aids starting ofthe compressor and yet makes it possible to remove substantially all of the oil from the evaporator but prevents trapping of oil therein. In addition, the utilization of small ducts leading to a. larger suction line, the total area of which is substantially equal to the total cross-sectional area of the ducts, provides in effect a series of restricted openings or orifices which increase the velocity and thereby facilitate the removal of oil.

Referring particularly to the modification shown in Fig. 5, the construction is similar to that previously described with the exception that the drum 18 is formed in the center of the upper section and the depressed portion 19 is omitted. The refrigerant may therefore circulate in both directions across the top of the outer corrugations. With this exception the operation of the evaporator shown in Fig. 5 is also similar to that previously described.

Referring more particularly to the modification shown in Figs. 6 and '7 the construction is similar to that shown in Figs. 1 to 4 with the exception that the headers 8 and 9 are omitted and the space 12 between the pairs of shells ordinarily fixed by the headers is filled with some suitable solid material which may be an insulating material or merely a poor heat conductor. The headers 8 are omitted to prevent any heat transfer between the inner shells 1 and 2 and the outer shells 3 and 4, the two refrigerant chambers constituting the two series of corrugations 6 and '7 are thereby substantially independent of each other although in communication with each other through opening 16. The inclusion of the filling matter also prevents condensation from occurring upon the surfaces of the walls defining chamber 12 and provides for greater independence and efficiency of action at the two refrigerant chambers.

A further modification is illustrated in this form comprising a transverse header 26 extending longitudinally across the bottom of the corrugations 6 and establishing communication to each of them. The inlet 22 is brought into this header instead of into opening 16. In this form the drum 18 is shown as in Figs. 1 and 4 although it is obvious that it may be arranged as is shown in Fig. 5. It is also apparent that the form shown in Figs. 1 to 4 may be provided with solid filling matter as is above described.

The operation of the evaporator shown in Figs. 6 and 7 is substantially the same as heretofore described with the exception that the incoming liquid refrigerant is brought into the bottom of corrugation 6 instead of the top.

It follows from the foregoing that there has been provided an evaporator which requires very little refrigerant and which is very efficient in operation. The evaporator is also substantially non-dehydrating, self-defrosting, and prevents the accumulation of any substantial amounts of oil therein.

It is obvious that many changes may be made -in the details of construction without departing from the spirit and scope of the invention as defined in the claims appended hereto.

I claim:

1. An evaporator comprising a pair of shells arranged one within the other, one of said shells being corrugated and secured to the other to provide a plurality of refrigerant ducts therebetween, said ducts being in communication with eachother at their ends, a second pair of shells spaced from each other and surrounding the first pair, the chamber between said latter pair of shells being in communication with said refrigerant ducts at the upper end of said chamber,

one direction only.

means for admitting refrigerant into said ducts and an outlet connection to said chamber between said latter two shells.

2. An evaporator comprising a pair of shells arranged one within the other, one of said shells being corrugated and secured to the other to provide a plurality of refrigerant ducts therebetween, said ducts being in communication with each other at their ends, a second pair of shells spaced from each other and surrounding the first pair, the chamber between said latter two shells being in communication with said refrigerant ducts at the upper ends of. said ducts, means for admitting refrigerant into said ducts and an outlet connection to said chamber between said latter two shells, said refrigerant ducts and said chamber being insulated from each other, except at the point of communication therebetween.

3. An evaporator comprising a pair of shells arranged one within the other, one of said shells being corrugated and secured to the other to provide a plurality of refrigerant ducts therebetween, a second pair of shells, arranged one within the other, and surrounding the first pair, the chamber between said latter two shells being in communication with said refrigerant ducts at the upper ends of the latter, means for admitting refrigerant into said duct and an outlet connection to said chamber between said latter two shells, the chamber between said pairs of shells being filled with a solid material of poor thermo-conductivity.

4. An evaporator comprising a pair of shells arranged one within the other and spaced to provide a refrigerant chamber therebetween, a second pair of shells arranged -one within the other and surrounding said first pair of shells, one of said latter pair of shells being corrugated to provide a plurality of refrigerant ducts therebetween said ducts being in communication with said first mentioned refrigerant chamber at the upper ends of said ducts, means for admitting refrigerant into said first chamber and an outlet connection communicating with said ducts.

5. An evaporator comprising a pair of shells arranged one within the other, one of said shells being corrugated and secured to the other to provide a plurality of refrigerant ducts therebetween, a second pair of shells arranged one within the other surrounding the first pair, one of said latter shells being corrugated to provide a plurality of communicating refrigerant ducts therebetween, said refrigerant ducts of each pair of shells being in communication with each other at their upper ends, means for admitting refrigerant into one set of ducts and an outlet connection to the other set of ducts.

6. An evaporatorcomprising a pair of shells arranged one within the other, one of said shells being corrugated and secured to the other to provide a plurality of communicating refrigerant ducts therebetween, a second pair of shells arranged one within the other and surrounding the first pair, one of said latter shells being corrugated to provide a plurality of refrigerant ducts therebetween, said refrigerating ducts of each pair of shells being in communication with each other, means for admitting refrigerant into one set of ducts and an outlet connection to the other set of ducts, and means for providing circulation of refrigerant through the outer set of ducts in 7. An evaporator comprising a pair of shells arranged one within the other, one of said shells being corrugated and secured to the other to provide a plurality of refrigerant ducts therebetween, a second pair of shells arranged one within the other and surrounding the first pair, the chamber between said latter two shells being in communication with said refrigerant ducts at, the upper ends of the latter, means for admitting refrigerant into said-ducts and an outlet connection to said chamber between said latter two shells, said refrigerant ducts and said refrigerant chamber being insulated from each other..

8. An evaporator comprising a pair of shells arranged one within the other, one of said shells being corrugated and secured to the other to provide a plurality of communicating refrigerant ducts therebetween, a second pair of shells arranged one within the other and surrounding the first pair, one of said latter shells being corrugated to provide a plurality of communicating ducts, the refrigerant ducts of each pair of shells being in communication with each other at their upper ends, means for admitting refrigerant into one set of ducts and an outlet connection to the other set of ducts, said pairs of shells being insulated from each other except at the point of communication.

9. An evaporator comprising a pair of shells arranged one within the other, one of said shells being corrugated and secured to each other to provide a plurality of refrigerant ducts therebetween, a transverse duct connecting said first mentioned ducts, a second pair of shells arranged one within the other and surrounding said first pair, one of said second shells being corrugated to provide a second set of refrigerant ducts therebetween, a second transverse duct connecting said second set of refrigerant ducts, said sets of ducts being in communication with each other at their upper ends, means for admitting refrigerant into one of said transverse ducts and an outlet connection to the other of said transverse ducts.

10. An evaporator comprising a pair of shellsarranged one within the other, one of said shells being corrugated and secured to the other to provide a plurality of refrigerant ducts therebetween, a transverse duct connecting said corrugations, a second pair of shells arranged one within the other and surrounding said first pair, one of said second shells being corrugated to provide a plurality of ducts therebetween, a transverse duct connecting said latter refrigerating ducts, said sets of ducts being in communication with each other, means for admitting refrigerant into one of said transverse ducts and an outlet connection to the other of said transverse ducts, and means for causing the refrigerant to travel in one direction only in the outer set of said refrigerant ducts.

11. An evaporator comprising a pair of shells arranged one within the other, one of said shells being corrugated and secured to the other to provide a plurality of refrigerant ducts therebetween, a transverse duct at the bottom of said first mentioned ducts for establishing communication therebetween, a second pair of shells arranged one within the other and surrounding said first pair of shells, one of said second shells being corrugated to form a plurality of refrigerant ducts therebetween, a transverse duct at the top of said second pair of shells in communication with said second set of ducts, said two sets of ducts being in communication with each other, means for admitting refrigerant into said first mentioned transverse duct and an outlet connection to the second mentioned transverse duct.

CARL E. L. LIP MT. 

